Synthesis and x-ray crystal structure of 11-bromo-endo-9-chloro-7-ethoxybicyclo[5.3.1]undec-1(11)-ene. A stable highly strained anti-Bredt olefin

Notably Enhanced Reactivity of the Fulleroid anti‐Bredt Double Bond in Diels–Alder Reactions

“…[27] Such strained bridgehead double bonds, so called anti-Bredt olefins, are known to increase the reactivity of some reactions such as 1,3-dipolar addition and MCPBA epoxidation. According to Bickelhaupt's technique, [28] we obtained the π-orbital misalignment (τ) [29] and the averaged pyramidality (χ av ) [29,30] of the bridgehead double bond along with the orbital energies (LU, LU + 1, LU + 2) by B3LYP/6-31G* calculations as shown in Table 2. Table 2.…”

A theoretical study for the regioselective Diels–Alder reaction of 5,6‐fulleroid with strained anti‐Bredt olefins

“…For the evaluation of carbon pyramidality and olefin strain, π‐orbital axis vector (POAV) angle θ p(avg) (POAV was calculated by a Excel sheet available in the website of Carbon Solutions, Inc. [founded by R. C. Haddon] http://www.carbonsolution.com/pyramidalization-poav) and π‐orbital misalignment angle ϕ were calculated as shown in Figure .…”

“…For the evaluation of carbon pyramidality and olefin strain, p-orbital axis vector (POAV) angle u p(avg) [37,38] p-orbital misalignment angle / [39] were calculated as shown in Figure 2.…”

Electrocyclic Ring-Opening Reactions of gem-Dibromocyclopropanes in the Synthesis of Natural Products and Related Compounds

“…Bickelhaupt and his group skilfully extended the cyclopropyl-to-allyl ring opening by fusing a ring of larger than six members across the gem-dibromobicyclo[3.1.0]hexane. Isolation of the ring-opened product becomes possible 109 as illustrated for the tricyclo[5.3.1.0 1,7 ]undecane 85. Simply heating the compound in ethanol effects the cyclopropyl-allyl ring opening and the bridgehead olefin is trapped quantitatively by the solvent to give the trans product whose structure was determined by X-ray crystallography.…”